import { toByteArray } from 'base64-js'
import Compressor from 'compressorjs'

// 根据base64转为file
export function  base64ToFile(base64String, fileName) {
    const arr = base64String.split(',')
    const mime = arr[0].match(/:(.*?);/)[1]
    const bstr = toByteArray(arr[1])
    const file = new File([new Uint8Array(bstr)], fileName, { type: mime })
    return file
}

// 压缩file(compressFileSize:压缩到指定大小，比如2M则compressFileSize为2,不指定则默认只压缩一次)
export function  compressFileByCompressor(file,compressFileSize) {
    console.log('压缩前大小：',file.size);
    let resultFile
    new Compressor(file, {
        quality: 0.6, // 压缩质量
        success(result) {
            // 压缩成功后，将压缩后的图片转为base64并返回
            const reader = new FileReader()
            reader.readAsDataURL(result)
            reader.onload = () => {
                const base64 = reader.result
                let newFile = self.base64ToFile(base64, 'text')
                console.log('压缩后大小：', newFile.size)
                if(compressFileSize && compressFileSize >0){
                    if (newFile.size > compressFileSize * 1024 * 1024) {
                        compressFile(newFile)
                    } else {
                        resultFile = newFile
                    }
                } else {
                    resultFile = newFile
                }
            }
        },
        error(err) {
            console.log(err.message)
        }
    })
    return resultFile
}

// 压缩img 传入img标签，并且src存在base64
export function compressFileByCanvas(img) {
    let canvas = document.createElement('canvas')
    let ctx = canvas.getContext('2d')
    //瓦片canvas
    let tCanvas = document.createElement('canvas')
    let tctx = tCanvas.getContext('2d')
    // let initSize = img.src.length;
    let width = img.width
    let height = img.height
    //如果图片大于四百万像素，计算压缩比并将大小压至400万以下
    let ratio
    if ((ratio = (width * height) / 4000000) > 1) {
        // console.log("大于400万像素");
        ratio = Math.sqrt(ratio)
        width /= ratio
        height /= ratio
    } else {
        ratio = 1
    }
    canvas.width = width
    canvas.height = height
    // 铺底色
    ctx.fillStyle = '#fff'
    ctx.fillRect(0, 0, canvas.width, canvas.height)
    //如果图片像素大于100万则使用瓦片绘制
    let count
    if ((count = (width * height) / 1000000) > 1) {
        count = ~~(Math.sqrt(count) + 1) //计算要分成多少块瓦片
        //            计算每块瓦片的宽和高
        let nw = ~~(width / count)
        let nh = ~~(height / count)
        tCanvas.width = nw
        tCanvas.height = nh
        for (let i = 0; i < count; i++) {
            for (let j = 0; j < count; j++) {
                tctx.drawImage(
                    img,
                    i * nw * ratio,
                    j * nh * ratio,
                    nw * ratio,
                    nh * ratio,
                    0,
                    0,
                    nw,
                    nh
                )
                ctx.drawImage(tCanvas, i * nw, j * nh, nw, nh)
            }
        }
    } else {
        ctx.drawImage(img, 0, 0, width, height)
    }
    //进行最小压缩
    let ndata = canvas.toDataURL('image/jpeg', 0.6)
    tCanvas.width = tCanvas.height = canvas.width = canvas.height = 0
    return ndata
}
